1. Field of the Invention
Generally in the internal combustion diesel engine for a varying vehicle, this invention relates to improvements in and concerning the connection structure for a branch pipe in a high-pressure manifold, particularly a manifold for handling a fuel under an ultra-high pressure exceeding 1,000 kg/cm.sup.3, which is disposed near the engine as a path for supply of the fuel to the engine.
2. Description of the Prior Art
In recent years, a connection structure which, as illustrated in FIG. 3, for example, comprises a plurality of through holes (13) which are formed as arranged in the longitudinal direction in the peripheral wall of a main pipe (11) serving to pass a high-pressure fuel and adapted to communicate with inner flow paths (12) and branch pipes (14) which are inserted one each into the through holes (13) and joined thereto by means of soldering or welding (W) has been trially put to use.
In the connection structure of this nature, however, the welded portions (W) are liable to be embrittled possibly to the extent of entailing the phenomenon of fuel leakage or the separation of branch pipes (14) from the main pipe (11) because the portions involved in the mutual insertion mentioned above fail to offer strength necessary for stable connection and the union of these portions by welding often suffers from poor workmanship and because these portions by nature are exposed to repeated application of an ultra-high fluid pressure frequently exceeding 1,000 kg/cm.sup.3 owing to the improvement in the engine construction and to incessant exertion of vibrations generated by the engine.